Internet of Things (IoT) is more and more widely used in the next generation of mobile communications networks. A traffic of IoT has many new features, including extra low power consumption requirement, deployment of massive user equipment (UE), relatively less flow of data, and low requirement on traffic latency, etc. Such features pose many technical requirements to an LTE (long term evolution) system, in which an important requirement includes that behaviors of UE should be power saving as possible.
A new wireless communications technology for supporting IoT traffics, i.e. a subject of a technology of narrow band Internet of Things (NB-IoT), is under study in the 3rd generation partnership project (3GPP). The NB-IoT technology is a new narrow band communications technology based on the existing LTE technology and enhanced to satisfy IoT traffic demands.
A scheme for paging a UE, especially a scheme for paging a UE in an idle state, existing in an NB-IoT and an LTE system, requires power saving as much as possible. In an existing paging scheme, within each paging cycle and at a subframe in a specified system frame number (SFN), the UE monitors a paging message transmitted by the network. The system frame where the UE monitors the paging is referred to as a paging frame (PF), and the subframe in the PF monitoring the paging is referred to as a paging occasion (PO).
For example, a formula used by each UE for calculating its PF and PO is as follows: SFN mod T=(T div N)*(UE_ID mod N), i_s=floor(UE_ID/N) mod Ns; where, SFN and i_s respectively determine positions of the PF and the PO, and parameters N, T, Ns, and nB, etc., are configured by the network, such as N: min(T, nB), Ns: max(1, nB/T), UE_ID=IMSI mod 1024. An international mobile subscriber identity (IMSI) is a numeral value fixed in the UE, and nB is a parameter broadcasted by the network in system information, and denotes a total number of POs of a cell within a paging cycle.
When a UE has arrived data, a mobility management entity (MME) transmits a paging message to a base station (such as an eNB), and the base station transmits a paging message within a PO of the UE. The paging message is carried by, for example, a physical downlink shared channel (PDSCH) indicated by downlink control information (DCI) in a physical downlink control channel (PDCCH). After the UE decodes the paging message on the PDSCH, if a UE identity in the paging message is identical to that of itself, it shows that the UE is paged, and a connection establishment request should be initiated.
It should be noted that the above description of the background is merely provided for clear and complete explanation of this disclosure and for easy understanding by those skilled in the art. And it should not be understood that the above technical solution is known to those skilled in the art as it is described in the background of this disclosure.